1. Technical Field
This invention relates to an image projection system and, more particularly, to an image projection system that generates an energy efficient image by selectively directing projection light onto a spatial light modulator.
2. Discussion of Related Art
Image projection system for projecting images onto a remote viewing area are generally known. Early versions of these image projection systems utilized relatively low intensity light sources for providing a projection light which is in turn used to project an image formed on its spatial light modulator to a distance viewing area. The resulting image displayed in the viewing area was large enough to be viewed by a group gathered within a relatively dark viewing area. However, the displayed image was often washed out by ambient light in brighter viewing environments, thereby limiting the usefulness of these image projection systems.
To overcome the problems associated with bright viewing environments, high intensity light sources were used in the image projection systems to generate the necessary projection light for displaying an image. While these image projection systems produced a displayed image which could be seen in bright ambient light conditions, the use of these light sources remained somewhat inefficient and costly. In these conventional image projection systems, a spatial light modulator was entirely flooded by its light source (typically an arc lamp) and then modulated with the desired image. The spatial light modulator, working with the polarizers normally found in such systems, effectively blocks the light from the light source in non-image areas while passing light in the desired image areas. Thus, these image projection systems inefficiently used the projection light from its light source since much of its energy does not produce the resultant displayed image. Therefore, it is desirable to provide a high resolution and energy efficient image projection system.
In accordance with the teachings of the preferred embodiment, an image projection system is provided for generating an energy efficient output representative of a desired input image. The image projection system includes a light source positioning device for directing the light from a light source onto a spatial light modulator. An image source provides the desired image to the spatial light modulator and also image information to a light source position controller for coordinating the light source positioning device, such that the light from the light source impinges substantially only the area of the spatial light modulator which contains the desired image.
The image projection system of the present invention better utilizes its light source by directing light only to the area on the spatial light modulator which contains the desired image. Using narrow angle light sources, such as lasers, helps to give a tremendous depth of field when compared to a normal arc lamp. In addition, the present invention reduces laser speckles as well as eliminates off state leakage by the spatial light modulator.